"One person can't save another person, but almost," Rosanne Cash once said about her father meeting the super-producer Rick Rubin. The union between the veteran country singer and the famed producer began in 1993 and resulted in a series of six albums (and a box set of outtakes) that revitalised Cash, both critically and commercially. He had spent the best part of 20 years in the wilderness, but the recordings re-established Johnny Cash as a great American artist – doubtless helped by their mythic banner name of "American" – and slowly restored him to public favour, too. Their first album, 1994's American Recordings, only made No 23 on the US country music chart and 110 on the Billboard 200 (though they were his highest placings on those charts since 1978 and 1971, respectively), and its follow-up, Unchained, fared worse. However, by 2002's American IV: The Man Comes Around, the man truly had come around. Propelled by the video for a cover of Nine Inch Nails' Hurt, the album went platinum in the US and cracked the top 40 here; then, after his death in 2003, Cash had his first No 1 album since 1969's At San Quentin with 2006's American V: A Hundred Highways.

American V was just the first in a slew of posthumous releases that includes 2010's American VI: Ain't No Grave, compilations of unreleased material (a four-volume bootleg series), expanded editions of classic albums and numerous greatest-hits packages. In total, press cuttings list 37 compilations on a variety of labels since his death, plus one collaboration album, one gospel album, two live albums and three studio albums. The best of these releases were bought in large numbers (American VI, the last album proper, has sold 250,000 copies in the US and 62,000 in the UK) and it's into this fertile environment that Cash's estate, which is privately owned by his family, is now releasing a "lost" record from the early 1980s, Out Among the Stars.

"It's being treated as a new Johnny Cash album and being given the full frontline marketing treatment," says Phil Savill, vice president of Sony Commercial Group UK. "We're expecting it to do very well." Accordingly, Forbes senior editor Zack O'Malley Greenburg will be paying attention when he starts crunching numbers for the magazine's annual top-earning dead musicians list. "Johnny Cash has been in the ballpark for the Forbes list every year, and he'll definitely be on our radar in 2014 with the new album coming out," he says. "He's one of the rare artists that continues to hold his appeal – musically and commercially – from generation to generation."

Is Johnny Cash bigger now than he ever was when he was alive? "It seems so," says Rick Rubin. "I think it may be a combination of the way the music of his last years connected to a new, younger audience, the film [2005's Walk the Line, starring Joaquin Phoenix and Reese Witherspoon], and the general recognition of the great loss of an American icon. At the time we started working together, Johnny had been relegated to playing small dinner theatres. The American Recordings series and some of the choices we made to support them – performances at the then-fledgling SXSW, Johnny Depp's Viper Room in Los Angeles and the Fez in New York – reminded people how much Johnny Cash was a part of their life and gave young kids in black T-shirts a glimpse of why Johnny was so cool decades earlier."

But there are some ironies here. Out Among the Stars is being released by a division of Columbia (now under the ownership of Sony), the label that dropped Cash in 1986, soon after these songs were recorded. He claimed to be "invisible" to Columbia at the time, despite having been a major figure on the label for 28 years, and his albums hadn't been given anything like "the full frontline marketing treatment" in years. Cash said of that period in his career: "The magic of the music was gone and I was just doing it because I do it, and I hate to think back on those years."

In 1984, soon after he'd spent 43 days in rehab at the Betty Ford clinic in California, Cash recorded a novelty song called Chicken in Black with famed country music producer Billy Sherrill, practitioner of a slicker, poppier sound dubbed "countrypolitan". Described by Rosanne Cash as a "nadir", it tells the tale of two brain transplants – Cash gets a bank robber's, a chicken gets his; Cash becomes a criminal, the chicken is offered a 10-year recording contract – and it came complete with an excruciatingly goofy video.

Contrary to popular belief, the song was not a middle-finger salute to Columbia; rather, it was an attempt to give Cash his first hit since 1979's (Ghost) Riders in the Sky. He initially backed the single, only demanding it be pulled, along with the video, after his family and friends had expressed alarm. Columbia was furious – the song had started to sell – and, in the chaos, a potential full album of Cash's recordings with Sherrill was shelved.

'The charts don't show big hits, but some beautiful music was being recorded [at this time]. But the world hadn't yet come back round to Johnny Cash' – John Carter Cash

Cash had been produced by Sherrill before – in 1980 and 1981 for an album called The Baron – and it's two songs left from the 1981 sessions as well as most of the material they recorded in 1984 (a further 10 tracks) that make up Out Among the Stars. As such, it's not a lost Johnny Cash album, but a compilation of the best unheard songs he cut with Sherrill, some of which were unfinished. Discovered in 2012 by John Carter Cash, Johnny's only child with his second wife, June Carter, they've been remastered, fiddled with and added to – including guitarist Marty Stuart rerecording some of his parts from the original sessions.

"The charts don't show big hits, but for the fans searching through this time period, there's some marvellous music, as well as some stuff that doesn't stand up to other times in his life," says Carter Cash. "There was some beautiful music that was being recorded and this album is one of those things. But the world hadn't yet come back round to Johnny Cash."

Cash's fallow years stretched from soon after his national TV show was cancelled in 1971 to when he started working with Rubin in 1993. If you dig deep, his son is right: there is plenty of good music to discover and it's notable that probably his best album from that era, Johnny 99, was released in 1983 – a year before the ill-fated Sherrill album would have been. That makes Out Among the Stars far more than just a curiosity for fans, though it's too much of a stretch to imagine it might have sold well in 1984, even in its current polished state. As Robert Hilburn wrote in his 2013 biography, Johnny Cash: The Life, Cash was still a concert pull in the 1980s, especially in Europe, but nobody was listening to his new music. He was forced to audition at one major label after being released by Columbia (it didn't get back to him), then he feared that Mercury, which signed him in 1987, was pressing only 500 copies of his albums.

'Some people just want to listen to greatest-hits albums, others want to hear all of an artist's output, their last works, or lost works, or demos. I don't see an issue with letting fans decide' – Rick Rubin

So the release of Out Among the Stars tells us as much about Johnny Cash's stature as an artist in 2014 – and the industry behind him – as it does about him in the early 1980s. "If you were going through your attic and found a Van Gogh, what would you do?" asks John Carter Cash, who acts as spokesman for his father's estate. "You wouldn't put it in your bathroom; you'd want to share it with the world because you know people will love it. I mean, we could stop putting out new material and the classic material would still sell, but why not release something new if it's beautiful?"

"I welcome new recordings by artists of historical importance because it helps give us a more complete picture of their artistry and career," Hilburn says. "There used to be lots of debate over this issue – as far back as the 1970s – but I think the acceptance of 'unreleased material' is by now a generally positive factor in pop culture."

John Carter Cash says there's much more still to come: four or five new albums from various points in his father's career – if the estate chooses to release everything – including plenty of unheard material from his sessions with Rubin.

Sony Legacy Recordings, which is releasing Out Among the Stars, will remain on-side. "Having met John and seen the love he has for his dad, we feel comfortable carrying out his wishes," Phil Savill says. He does admit, though, that the response to the new album will affect how Sony markets future releases. "The success of this one will impact on the scale of support we give any future albums, but Johnny Cash is the kind of artist that has a fanbase that will always be interested in hearing archive material. We'll always be putting out Johnny Cash releases so long as the quality of material is there and they're supported by John Carter Cash."

But isn't there a point where new albums no longer offer greater understanding of an artist's craft and history, just more music?

"It's a question of doing what's right," says Carter Cash. "It's a matter of integrity and not cashing in, as I've heard people say."

"It's hard to say," Rubin says. "Some people just want to listen to greatest-hits albums, others want to hear all of an artist's output, or their last works, or lost works, or demos. I don't see an issue with letting fans decide what they want to listen to from an artist. If they don't like it, don't buy it. I literally have hundred of albums of Beatles outtakes and alternate performances and I love hearing the evolution of the songs, and songs they chose not to release. It's a pretty personal decision."